Atlanta , Georgia -LRB- CNN -RRB- -- Julia Lynn Womack Turner , who was convicted in 2007 of murder for the deaths by antifreeze poisoning of her boyfriend and husband , died Monday in prison in Georgia , prison officials said .

Turner `` was found unresponsive in her cell at 6:55 a.m. , at which time prison medical staff and EMS responded but were unable to revive her , '' the Georgia Department of Corrections said in a statement .

The cause of death was under investigation by the Georgia Bureau of Investigation 's medical examiner 's office . Turner was serving life without parole in the Metro State Prison for women in Atlanta .

Turner was convicted of murder for the 1995 death of her husband , police officer Glenn Turner , and for the 2001 death of her boyfriend , firefighter Randy Thompson , both of whom were poisoned with antifreeze .

Glenn Turner died March 3 , 1995 , from what was initially determined to be an irregular heartbeat . A week later , Turner moved in with Thompson , with whom she had begun an affair several months prior .

But it was not until Thompson died in 2001 under similar circumstances that authorities exhumed the body of Glenn Turner and performed another autopsy .

In both cases , the men had exhibited flulike symptoms before being taken to the emergency room . They both died less than 24 hours after they left the hospital , from what a coroner initially identified as heart failure .

Further examination , however , revealed traces of ethylene glycol , a byproduct of antifreeze , in both of their bodies . Cobb County prosecutors labeled the defendant a `` black widow '' who murdered both men for financial gain .

After her husband 's death , Turner received more than $ 150,000 in benefits and interest from his life insurance and pension . She received about $ 36,000 from Thompson 's death .

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Julia Lynn Turner was convicted in 2007 of murder

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She poisoned her husband in 1995 and boyfriend in 2001

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Both men were found to have died from antifreeze poisoning

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The Georgia Bureau of Investigation will determine Turner 's cause of death